Foundation of Biology Exam Four

What separates plants from algae

• Alternation of generations

• Spores

• Apical Meristems

• cuticle

• Stomata

Alternation of generations

Type of life cycle consisting of forms that give rise to each other (aka gametophyte and sporophyte stages)

Spores

Polymer sporopollen makes walls of plant spores resistant to harsh environments

meristems 

Cells in plants that become any type of cell. Enables continued plant growth throughout it’s life and asexual reproduction.

• Apical: enables to growth in length

• Lateral: enables growth in thickness

Cuticle

Waxy substance that prevents the plant from drying out

Stomata

Allowing exchange of CO₂ and O₂

Vascular plants 

Most plants have an extensive system of vascular tissue (xylem and Phloem)

Broyophytes

• Non-vascular plants, paraphyletic group, mosses and liverworts

• Haploid gametophyte generate is dominant 

• Swimming sperm 

• Disperse via spores 

• Thin cuticle 

• Self-fertilize most of the time 

Seed

• Plant embryo packed with a supply of nutrients 

• Packed with cotylean (food source)

Gymnosperms

Seeds not enclosed in chambers (non-flowering)

Angiosperms

Seed develop within chambers (flowering)

Root 

Anchors vascular plants to the soil and allows for the uptake of water and minerals 

Stem

Plant organs bearing leaves and buds elongates the shoot to maximize photosynthesis

Leaf

Main photosynthetic organ, exchanges gases and dissipates heat.

Vascular tissue 

Facilitates the transport of nutrients through the plant and provide mechanical support

Xyelm

Transports water and minerals through vascular plants

Phloem

Transports sugars through vascular plants

indeterminate growth 

Plants can keep growing throughout their entire life 

Cell Wall

protects plant cell walls and maintains shape

Plasmodesmata 

Channels that connect plant cells 

Prophase I

• Crossing over occurs

• Microtubules are attached to the kinetochores of each homologue

Metaphase I

• Each pair of homologous chromosomes lines up at the metaphase plate independently of other pairs

Anaphase I 

• Homologues seperate 

• Sister chromatids remains together 

Telophase I

• Cell splits

• Each cell has a haploid set of duplicated chromosomes with sister chromosomes with non-indentical DNA (due to crossing over)

Prophase II

• Spindle forms and microtubules attach to the kinetochores of each sister chromatid

Metaphase II

• Chromosomes line up at the metaphase plate 

Anaphase II

• Sister chromatids are split apart and pulled to opposite sides of the cell

Telophase II

• cells seperate

• The result is four daughter cells that are haploid and genetically distinct

Independent assortment 

Maternal and paternal chromosomes can face different ways during metaphase I making it possible for a cell to have maternal chromosomes of some traits and paternal chromosomes of others  

Recombinate chromosomes

Chromosomes that carry genes from two different parents due to crossing over in prophase I

Gametophyte

Produces gametes (haploid part of a plant)

Sporophyte 

Produces spores (diploid part of the plant)

Bryophyte life cycle

• Spores produced via meiosis disperse and develop into a gametophyte

• Sperm and eggs (produced via mitosis) develop in the gametangium of the gametophyte and fertilize to form a diploid zygote

• The zygote develops into an embryo which gives rise to a diploid sporophyte

• Spores develop (via meiosis) in the sporophyte’s sporangium and disperse

Seedless vascular plants (ferns)

• Vascular system

  • xylem

  • phloem

  • Liginin (strengthens xylem cell walls)

• Taller growth

• Transport substances longer distances

• Tissue specialization

• Sporophyte dominated life cycle

• Swimming sperm

Sporophylls 

Specialized leaves where spores form 

Fern life cycle 

• Spores develop via meiosis 

• Spores develop into the gametophyte 

• Sperm and eggs (produced via mitosis) develop in the gametangium of the gametophyte and fertilize to form a diploid zygote

• Zygote divides to form an embryo which gives rise to a diploid (independent and photosynthetic) sporophyte

• Spores develop (via meiosis) and are released from the sporangia on the leaves of the sporophyte

Homosporous

Only one kind of spore (most seedless plants)

Heterosporous

• Two kinds of spores

• Megasporangia: Megaspores (female)

• Microsporangia; microspores (male)

Ovule 

• Female gametophyte develops within ovule 

• Produces eggs via mitosis 

Pollen

• Male gametophyte enclosed within pollen wall

• Pollen grows pollen tube and releases sperm into egg

Advantages of seeds

• Can remain dormant for longer than spores

• Have stored food

• Adaptations for dispersal

Gymnosperm (pine) life cycle 

• Haploid pollen grains (develop via meiosis)

• Haploid spore cells develop into female gametophyte which produces eggs 

• Pollination happens 

• The pollen grows a tube and releases sperm that fertilizes the egg 

• An embryo develops which becomes a new sporophyte after developing 

Flower

Structure specialized for reproduction that bears seeds in a protective chamber (ovary)

• sepals: encloses the flower before it opens

• petals: attracts pollinators

• Stamens: produces pollen

• ovule: Produces embryo sac

Angiosperm life cycle 

• Haploid spores in the anters develop into pollen grains (meiosis)

• Haploid spore in each ovule develops into a female gametophyte which produces eggs

• Pollination and growth of the pollen tube

• Fertilization forms a zygote 

• The ovary develops into a fruit to protect the seeds and aid in dispersal 

• Seeds develop into a new sporophyte 

Fruit

• Mature ovary

• Mechanism for seed dispersal

• May protect dormat seeds